Inflator and airbag module

ABSTRACT

An inflator for a protective device in a vehicle includes a diffuser ( 10 ) forming a substantially rotation-symmetric external housing of the inflator with a closing member ( 12 ), wherein the diffuser ( 10 ) includes a plurality of discharge orifices ( 78 ) arranged in a row, and which are of circular shape. The inflator also includes a filter ( 46 ) and a combustion chamber component at least partially enclosing at least one of a combustion chamber ( 56 ) and a combustion chamber sleeve ( 60 ), wherein the filter ( 46 ) extends in a ring-shaped manner about the combustion chamber ( 56 ) and, at a position of its ring-shaped extension, includes a critical filter portion ( 120 ) which is closer to the combustion chamber component than the remaining filter areas situated at its ring-shaped extension, wherein the critical filter portion ( 120 ) has a reduced thickness compared to areas of the filter that are adjacent to the critical filter portion ( 120 ).

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/878,827, filed Sep. 27, 2011, which corresponds to PCT/DE2011/001820,filed Sep. 27, 2011, and which claims the benefit of German ApplicationNo. 20 2010 014 288.5, filed Oct. 15, 2010, the subject matter of whichare incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

The invention relates to an inflator, especially for a protective devicein a vehicle. Furthermore the invention relates to an airbag module fora vehicle.

Inflators for protective devices in a vehicle are especially providedfor driving particular members (propping up of hoods, tensioning of thesafety belt, shifting of cushions or the like) or for inflating airbagsso as to prevent a vehicle occupant from impacting onto hard vehicleparts.

The requirements to the efficiency of an inflator in general are veryhigh. In an extremely short time a particular amount of gas must be madeavailable which shall not be too hot and preferably free of particles.An inflator also should be as light-weight as possible and requirelittle space so that e.g. in the case of mounting in a steering wheelparticular requirements of the steering wheel design can be observed.

SUMMARY OF THE INVENTION

The invention creates a compact and effective inflator having a veryefficient structure which satisfies the afore-mentioned requirements.

In accordance with a first major aspect of the invention, the inflatorespecially provided for a protective device in a vehicle comprises adiffuser which preferably forms a substantially rotation-symmetricexternal housing of the inflator with a closing member. The diffuserincludes more than 12, preferably more than 14, further preferably 23discharge orifices arranged in a row. The large number of dischargeorifices ensures a uniform gas discharge into the airbag. Moreover, thearrangement of the discharge orifices in a row permits an easy tampingat the inside of the diffuses e.g. by a narrow tamping strip.

If a sufficiently large number of discharge orifices in the row arechosen, it is sufficient that the diffuser includes only one single rowof discharge orifices.

It is preferred that the inflator is of a kind that has a diffuserwhich—related to the central axis A of the diffuser (10)—is surroundedby a fixation flange in a ring like manner.

An efficient configuration of the inflator according to the inventionprovides that the ratio of the outer circumference of the diffuser in mmto the number of the discharge orifices in a row is less than 16.5,preferably less than 14.1, further preferably less than 9.85, furtherpreferably it is between 7.57 and 9.85, further preferably between 8.20and 8.96 and further preferably it amounts to approx. 8.56.

An especially favorable gas discharge behavior results from the factthat the discharge orifices have at least two, preferably threedifferent cross-sections, wherein the discharge orifices are preferablycircular and the different flow cross-sections are defined by differentdiameters of the circular discharge orifices.

In accordance with an advantageous configuration, opposite dischargeorifices have the same flow cross-section—related to a central axis ofthe diffuser. As a matter of course, this is only applicable todischarge orifices which are in fact opposed to another dischargeorifice.

A further advantageous configuration provides that directly neighboringdischarge orifices have different flow cross-sections.

In a preferred embodiment of the invention, the discharge orifices haveat feast three different flow cross-sections. In the row of thedischarge orifices at feast partly a recurring sequence of the followingtype is provided: first flow cross-section→second flowcross-section→first flow cross-section→third flow cross-section.Preferably the first flow cross-section is small, the second flowcross-section is medium and the third flow cross-section is a large flowcross-section.

Moreover, the preferred embodiment of the invention provides that theratio of the outer circumference of the diffuser in mm to the number ofthe discharge orifices having the small flow cross-section is less than19.7, preferably between 15.1 and 19.7 and further preferably is approx.17.9.

As regards the other flow cross-sections, the preferred embodiment ofthe invention provides that the ratio of the outer circumference of thediffuser in mm to the number of the discharge orifices having the mediumflow cross-section and/or to the number of the discharge orifices havingthe large flow cross-section is less than 39.4, preferably rangesbetween 28.2 and 39.4 and further preferably is approx. 32.8.

As regards the gas discharge, a ratio of the total flow cross-section ofall discharge orifices of the row in mm² to the outer circumference ofthe diffuser in mm is advantageous which is more than 110, preferablyranges between 110 and 139 and further preferably is approx. 124.

The distances between neighboring discharge orifices in the row arepreferably equal.

According to a special arrangement of the discharge orifices, the row ofthe discharge orifices extends with respect to a central axis of thediffuser in the circumferential direction and has a beginning with afirst discharge orifice as well as an end with a last discharge orifice.The distance between the first and the last discharge orifices is largerthan, preferably twice as large as the distance between neighboringdischarge orifices in the row. Thus one discharge orifice isdeliberately “left out”.

In this event, the angular distance between neighboring dischargeorifices amounts to 360°/(n+1), with n being the number of the dischargeorifices in the row.

Between the beginning and the end of the row, i.e. in the area in whichdeliberately no discharge orifice is provided, a joint of a tampingstrip can be arranged.

In accordance with a second major aspect of the invention, the inflatorcomprises a fuel canister filled with fuel having a fuel canister bottomand a fuel canister opening opposed to the fuel canister bottom which isclosed by means of a combustion chamber component. The fuel canisterconstitutes an advantageous filling aid for the fuel which is closed bythe combustion chamber component only after filling.

In a preferred embodiment of the invention, the combustion chambercomponent is a combustion chamber sleeve which preferably at leastpartially encloses a combustion chamber associated with a particularactivating stage of the inflator, wherein the combustion chamber sleevehas a combustion chamber sleeve orifice or an open side and a combustionchamber sleeve bottom opposed thereto which covers the fuel canisteropening.

Especially useful is an arrangement of a filling body at the combustionchamber sleeve bottom which is preferably connected to the combustionchamber sleeve bottom, i.e. the combustion chamber sleeve and the fillmember constitute a pre-assembled unit. When closing the fuel canisterby the combustion chamber sleeve the fill member is automaticallydisposed in the combustion chamber enclosed by the combustion chambersleeve. This has the advantage that the filling body need not beseparately inserted and a correct positioning is ensured.

A defined arrangement of the combustion chamber sleeve relative to thefuel canister is preferably achieved in that at least a part of a sidewall of the fuel canister extending between the fuel canister openingand the fuel canister bottom is directly opposite to a part of a sidewall of the combustion chamber sleeve extending between the combustionchamber sleeve orifice or the open side of the combustion chamber sleeveand the combustion chamber sleeve bottom.

According to a particularly advantageous configuration, the fuelcanister and the combustion chamber sleeve can form a sleeve plug-insystem by designing the fuel canister and the combustion chamber sleevein the form of two open substantially cylindrical sleeves which areplugged into each other while being oriented opposed to each other sothat an inner or outer shell of the fuel canister and an outer or innershell of the combustion chamber sleeve substantially cover each otherover the entire axial length of the shells. The combustion chambersleeve is preferably slipped onto the outside of the fuel canister. Thisensures that the fuel chamber sleeve does not contact the fuel so as toexclude damage of the fuel and/or hindering a slip-on of the combustionchamber sleeve.

In order to reinforce the fuel canister, it may have a bead or fin inthe vicinity of the fuel canister opening which is preferably completelycircumferential in circumferential direction—related to a central axisof the fuel canister—. Thus undesired deformation when handling the fuelcanister can be counteracted.

For attaching the fuel canister in the inflator a central fuel canisterbottom opening can be advantageously formed in the fuel canister bottomto receive an igniter carrier.

In order to permit a stable support of the fuel canister the fuelcanister bottom opening is formed by a preferably bent inner edgeportion of the fuel canister bottom which extends from the fuel canisterbottom into the inside of the fuel canister. The edge portion can besupported on a holding surface of the carrier component.

Plural holes are preferably formed in the fuel canister bottom so thatthe gas formed during combustion of the fuel in the fuel canister canescape from the fuel canister.

On the other hand, the fuel chamber sleeve preferably is free of holes,apart from the combustion chamber sleeve orifice or the open side.

According to a preferred type of mounting, the combustion chamber sleeveis attached to an igniter carrier so that, if it is appropriatelydesigned as a press fit, no further mounting measure is required.

Preferred materials for the fuel canister are aluminum, copper, plasticmaterial or steel; the combustion chamber sleeve is preferably made ofsteel.

In accordance with a third major aspect of the invention, the inflatorcomprises a combustion chamber sleeve which at least partly encloses acombustion chamber filled with fuel. The combustion chamber sleeve isdesigned so that its position and/or shape are varied by a pressureformed during combustion of the fuel such that a discharge orifice isreleased for a combustion gas formed during combustion of the fuel. Thedischarge orifice leads out of the combustion chamber, preferably intoanother combustion chamber of the inflator. Such configuration permitsto completely dispense with discharge orifices during manufacture of thecombustion chamber sleeve, because the discharge orifice according tothe invention is formed as needed. Apart from the less complexmanufacture of the combustion chamber sleeve, this has the advantagethat no discharge orifices have to be sealed.

Accordingly, it is preferably provided that the combustion chambersleeve exhibits no discharge orifice prior to the combustion of thefuel.

In a preferred embodiment of the invention the combustion chamber sleevemoves toward a ceiling portion of a diffuser of the inflator due to thepressure formed during combustion of the fuel, wherein the movement ispreferably limited by the ceiling portion. Consequently, the pressureprevailing in the combustion chamber is used for a controlled movementof the combustion chamber sleeve.

A further development of this concept provides that the combustionchamber sleeve is partly supported on the ceiling portion of thediffuser, preferably already prior to activation of the inflator, andthat the pressure causes tilting and/or non-uniform deformation of thecombustion chamber sleeve. The tilting or deformation is deliberatelyforced so as to create the desired discharge orifice.

According to a preferred design, the combustion chamber sleeve isattached to a support component of the inflator, especially an ignitercarrier. The discharge orifice is formed by the fact that the combustionchamber sleeve detaches at least partially from the carrier component sothat a gap is formed between the combustion chamber sleeve and thecarrier component. The combustion gas can escape from the combustionchamber through the gap.

Of particular advantage is a structure designed such that thegap—related to a central axis of the combustion chamber sleeve—is formedto be not completely circumferential or at least not at a constantwidth. The gap has its largest width in an area facing away from afilter disposed outside the combustion chamber and/or having the largestpossible distance from the filter. Thus the filter can be prevented frombeing damaged, as the combustion gas impinges on the filter only afterovercoming a quite large distance or via a by-pass.

According to the special filling concept of the combustion chamber, thecombustion chamber sleeve is slipped onto the fuel canister filled withfuel and having a fuel canister bottom including one or more holesthrough which the combustion gas flows to the discharge orifice. In thisway a flow communication for the combustion gas from the fuel canisterto the discharge orifice is ensured by simple means.

When appropriately designing the fuel canister, the hole(s) in the fuelcanister bottom can also formed as late as by the pressure developedduring combustion of the fuel and tearing of the fuel canister bottomcaused thereby.

In accordance with a fourth major aspect of the invention, the inflatorcomprises an igniter sleeve which at least partially encloses an igniterand an igniter chamber especially filled with a boosting charge and isadjacent to a first combustion chamber filled especially with fuel. Theigniter sleeve includes—related to a central axis of the ignitersleeve—overflow orifices which are distributed non-uniformly incircumferential direction. It is the purpose of this measure to directthe hot gas overflowing from the igniter sleeve by which the fuel of theadjacent combustion chamber is ignited to preferred areas of thecombustion chamber, which permits optimum ignition of the fuel in thecombustion chamber.

In conformity with this concept, a predetermined orientation of theigniter sleeve can be determined such that the overflow orifices are notdirected directly to a filter disposed outside the igniter sleeve. Inthis way, the filter is not exposed to unnecessary load and damage ofthe filter by the hot gas overflowing from the igniter sleeve, to whichparticles are added, is prevented.

According to a particular development of this aspect of the invention,the igniter sleeve includes a marker distant from its central axis orextending non-symmetrically from the central axis which indicates thepredetermined orientation of the igniter sleeve. The marker assists inavoiding errors in mounting the igniter sleeve as regards theorientation thereof.

Especially a nose or a recess at the igniter sleeve is suited as marker.For mounting a tool carrier can be provided which includes a matchingrecess or nose and receives the igniter sleeve so that it isautomatically mounted in the inflator at the predetermined orientation.

In addition or as an alternative, a configuration of the igniter can beprovided which is adapted to the configuration of a neighboringcomponent of the inflator such that an assembly of the igniter sleeve inthe inflator is only possible at the predetermined orientation. In thisway mounting errors are practically completely excluded.

It may be provided, for instance, in an igniter sleeve offset withrespect to the central axis of a diffuser that a bottom of the ignitersleeve opposed to a ceiling portion of the diffuser exhibits a slantadapted to a curvature of the ceiling portion of the diffuser in suchfashion that the igniter sleeve fits below the ceiling portion of thediffuser only at the predetermined orientation.

The overflow orifices advantageously define at the predeterminedorientation of the igniter sleeve in circumferential direction a maximumangular area extending to both sides of a connecting line between thecentral axis of the igniter sleeve and the portion of the filtermaximally distant from the central axis. This is to save the filter atbest.

A design of the overflow orifices according to which the angular rangeincludes areas which have a maximum distance from the filter not blockedby components of the inflator permits an optimum “yield” of the ignitingjets emitting from the overflow orifices in accordance with a maximumeffective length. The fuel in the combustion chamber cannot beunderstood as component of the inflator in this context; on thecontrary: as much fuel as possible is to be covered by the igniting jetsof the burning booster charge between the igniter sleeve and the filter.

The angular area can also include a combustion chamber component,especially a combustion chamber sleeve, which surrounds a secondcombustion chamber which itself in turn is at least partly surrounded bythe first combustion chamber.

In a preferred embodiment the angular range is obtuse and preferably isbetween 90° and 135°, further preferably between 100° and 120° andfurther preferably amounts to approx. 110°.

With respect to optimizing the combustion chamber surrounding theigniter sleeve, it is advantageous to design the igniter sleeve so thatit is radially tapered in axial direction toward a bottom of the ignitersleeve. In this case, due to the tapering outside the igniter sleevemore space is provided for the fuel,

In accordance with a fifth major aspect of the invention, the inflatorcomprises an igniter sleeve which at least partially encloses an igniterand an igniter chamber especially filled with a booster charge and isadjacent to a first combustion chamber associated with a firstactivating step of the inflator. The inflator further comprises acombustion chamber sleeve which at least partially encloses a secondcombustion chamber filled with fuel and associated with a secondactivating step of the inflator. Both sleeves are juxtaposed and arepreferably differently offset with respect to a central axis of theinflator. This arrangement results in an extremely compact and efficientstructure of a two-stage inflator.

Especially efficient is a configuration in which the distance betweenthe central axes of the igniter sleeve and the combustion chamber sleeveis between 22.5 and 27.5 mm, preferably between 23.5 and 26.5 mm andfurther preferably amounts to approx. 25 mm.

The ratio of the minimum inner diameter of the combustion chamber sleeveto the minimum inner diameter of the igniter sleeve of preference isbetween 1.64 and 2.63, preferably between 1.83 and 2.32. Furtherpreferably this ratio amounts to approx. 2.06.

On the one hand, an optimum adjustment between the compact structure ofthe two-stage generator and an efficient cooling and filtering of thegenerated gas results from an at least partial radial restriction of thefirst combustion chamber by an at least partly circumferentialfilter—related to a central axis of the inflator—, wherein the ratio ofthe inner diameter of the filter to the minimum inner diameter of theigniter sleeve is between 3.19 and 4.76, preferably between 3.50 and4.27 and further preferably amounts to approx. 3.85.

On the other hand, in the case of such filter configuration an optimumadjustment is reached with a ratio of the inner diameter of the filterto the minimum inner diameter of the combustion chamber sleeve which isbetween 1.66 and 2.11, preferably between 1.76 and 1.99 and furtherpreferably amounts to approx. 1.87.

According to on efficient configuration of the inflator according to theinvention, the ratio of the outer diameter of the inflator to theminimum inner diameter of the igniter sleeve is between 4.09 and 5.98,preferably between 4.46 and 5.39, and further preferably amounts toabout 4.89. By the outer diameter of the inflator the outer diameter ofthe outermost inflator component has to be understood, for instance of adiffuser, wherein a laterally (radially) extending flange is not takeninto consideration.

According to another efficient configuration, the ratio of the outerdiameter of the inflator to the minimum inner diameter of the combustionchamber sleeve is between 2.13 and 2.66, preferably between 2.24 and2.50 and further preferably amounts to approx. 2.38.

A special design provides that the axial distance of an open side of theigniter sleeve from a bottom of a closing member of the inflator isunequal to the axial distance of an open side of the combustion chambersleeve from the bottom of the closing member, the distance of theigniter sleeve preferably being larger. Since the igniter sleeve and thecombustion chamber sleeve have different diameters, thereby the use ofcarrier components having a substantially equal structure is madepossible for both sleeves which can be mounted at the same height in theclosing member bottom and both have a first receiving portion adapted tothe igniter sleeve as well as a second receiving portion axially offsetto the former and adapted to the combustion chamber sleeve.

As regards the particular mechanism of the second activating stage inwhich the discharge orifice leading out of the combustion chamber sleeveis formed as late as by a pressurized raising of the combustion chambersleeve, a support of the igniter sleeve and the combustion chambersleeve is advantageous in which the igniter sleeve and the combustionchamber sleeve are attached onto a first igniter carrier and a secondigniter carrier, the axial height of the contact area between theigniter sleeve and the first igniter carrier being larger than the axialheight of the contact area between the combustion chamber sleeve and thesecond igniter carrier. The combustion chamber sleeve detaches from thesecond igniter carrier already after a slight axial displacement andthus releases the desired discharge orifice. Although in the ignitersleeve also an axial displacement can occur, a release of an(additional) discharge orifice is not provided, however.

Accordingly, a preferred embodiment of the inflator according to theinvention is designed such that both the igniter sleeve is raised by thepressure formed during combustion of the booster charge and thecombustion chamber sleeve is raised by the pressure formed duringcombustion of the fuel, preferably in the direction of the ceilingportion of a diffuser of the inflator. By raising the combustion chambersleeve a discharge orifice is released, preferably in the form of adischarge gap which leads out of the combustion chamber sleeve, whereasno discharge orifice is released by raising the igniter sleeve. Thelater is not desired, because in the igniter sleeve alreadyadvantageously positioned overflow orifices are provided which arereleased during combustion of the boosting charge at the latest.

Preferably the diffuser is designed so that a ceiling portion limits themovement of the igniter sleeve and the movement of the combustionchamber sleeve.

In accordance with a sixth major aspect of the invention, the inflatorcomprises a filter and a combustion chamber component at least partiallyenclosing a combustion chamber, in particular in a ring shaped manner,especially of a combustion chamber sleeve. The filter exhibits acritical filter portion which is closer to the combustion chambercomponent than the other filter areas situated along its ring shapedextension. The critical filter portion has a reduced thickness comparedto areas of the filter that are adjacent to the critical filter portion.Especially between the combustion chamber component and the criticalfilter portion a gap is formed. This measure constitutes a protectionagainst over-igniting, it has to be ensured that the fuel of the secondactivating stage is not automatically (thermally) ignited during andpossibly after combustion of the fuel of the first activating stage.Heat introduction to the fuel of the second activating stage by burningthe fuel of the first activating stage is not absolutely critical inthis context. However, heating of the liter and especially the heatradiation reflection (having a delaying effect) of the heated filtercould have negative effects, especially in the area close to thecombustion chamber of the second activating stage. The tapering of thecritical filter portion therefore creates a heat-insulating distance(air gap) between the filter and the combustion chamber component forreasons of precaution.

Preferably the material forming the filter is compressed more highly inthe critical filter portion than in the adjacent areas. The criticalfilter portion in this case can be manufactured simply by a spatiallylimited compression of the filter without material having to be abraded.

For further improvement, the combustion chamber component can have anincreased material thickness at least in the area opposed to thecritical filter portion. Optimum protection against over-igniting isresulting from the combination of the material thickening of thecombustion chamber component with the opposed filter tapering.

According to a preferred arrangement the filter extends along acircumferential wall of the inflator surrounding a chamber of theinflator in which the combustion chamber component is arranged.

In the case of a combustion chamber component which extends over alarger axial height than the filter, it is sufficient when thecombustion chamber component has an increased material thicknesssubstantially only in the axial area into which also the filter extends.Thus material expenses and weight can be saved.

According to an efficient configuration, the ratio of the minimumthickness of the critical filter portion to the thickness of theadjacent areas of the filter is between 0.43 and 0.93, preferablybetween 0.53 and 0.78, and further preferably amounts to approx. 0.65.

According to a further efficient configuration of the protection againstover-igniting, the ratio of the minimum thickness of the critical filterportion to the maximum width of the gap is between 1.17 and 2.85,preferably between 1.50 and 2.23, and further preferably amounts toapprox. 1.83.

A special design and arrangement of the filter provides that theinflator is closed at a first axial end face by a diffuser having asubstantially axially extending circumferential wall, the filterextending in axial direction beyond the circumferential wall.

In accordance with a seventh major aspect of the invention, the inflatorcomprises a circumferential wall which especially surrounds a combustionchamber and a filter which extends at least partly along the wall. Thewall includes at least one supporting portion. The supporting portionconstitutes an axial support for the filter and is formed preferablyintegrally with the wall. It is an advantage of this wall support forthe filter that inside the inflator the filter need not extendunnecessarily over the entire height, in this way filter material can besaved and more space is available for fuel in the combustion chamberonly partially surrounded by the filter in that case. An otherwiserequired separate supporting element can be dispensed with.

Either only one supporting portion formed by a completelycircumferential preferably embossed bead can be provided or else pluralsupporting portions can be formed by preferably embossed beads.According to the latter alternative the beads can be spaced apart fromeach other in circumferential direction.

According to a preferred embodiment, the inflator is closed at an axialend face by a closing member and the supporting portion(s) is/are formedin a pulled-up edge of the closing member.

An advantageous configuration provides that the filter is supported onlywith a radially outer area on the supposing portion or portions. In thecase of an embossed bead, the same thus need not extend inwardly overthe entire thickness of the annular filter.

In accordance with an eighth major aspect of the invention, the inflatorcomprises a first combustion chamber filled with fuel which isassociated with a first activating stage of the inflator and is closedat one side by a cover, especially a diffuser. Between the fuel and thecover a first fill member is disposed. The first fill member has atleast one, preferably circular, recess. A sleeve, especially an ignitersleeve associated with the first activating stage of the inflator, or acombustion chamber sleeve associated with a second activating stage ofthe inflator projects into the recess. A fill member of this design hasplural advantages, apart from fulfilling its main purpose, it supportsthe stability of the sleeve protruding into the recess as regardsundesired shifting or tilting in lateral direction. Moreover, thespecial configuration of the fill member allows an extremely compactshape in axial direction, as the sleeve protrudes into the fill memberso that the space between the sleeve and the cover can be minimized.

Especially in a two-stage inflator according to a preferred embodimentthe first fill member has two recesses of different size, whereinpreferably the igniter sleeve protrudes into the smaller recess and thecombustion chamber sleeve preferably protrudes into the larger recess.

An efficient configuration provides that the ratio of the diameter ofthe larger recess to the diameter of the smaller recess is between 1.52and 2.25, preferably between 1.67 and 2.03 and further preferablyamounts to approx. 1.84.

The manufacture of the first fill member can be simplified by designingthe first fill member at least in two parts. It is another advantage ofthe two-part design that during mounting the fill member largertolerances can be compensated than with a one-part design of the fillmember.

In this case, a design in which each of the two parts of the first fillmember has the shape of a double half moon is especially expedient. Thefill members then can have identical shapes and can be arrangedsymmetrically with respect to each other.

The preferred material for the fill member is silicone which, on the onehand, is resilient to keep the fuel under pressure so as to avoid noise.On the other hand, the silicone does not react, when the inflator isactivated, with the fuel or with components of the inflator in anundesired manner.

In accordance with a ninth major aspect of the invention, the inflatorcomprises a radially projecting generator flange—related to a centralaxis of the inflator—for mounting the inflator to a generator carrier.The generator flange substantially has a rectangular shape. Therectangular configuration of the generator flange permits a space-savingdesign of the generator carrier and of the construction spacesurrounding the inflator, especially when the flange is only slightlywider than the outer diameter of the external housing of the inflator.By a substantially rectangular shape one does not necessarily understanda perfect rectangle; basically rectangular shapes having roundedcorners, edge-side recesses etc. are also to be comprised.

It is provided in a preferred design that the inflator includes anexternal housing having a preferably circular cross-section whosecentral axis extends across the center of the generator flange.

Regarding the dimensions of the generator flange, for attaching theinflator to the generator carrier a length-to-width ratio of therectangle between 1.12 and 1.31, preferably between 1.16 and 1.27 hasturned out to be advantageous. Further preferably this ratio amounts toapprox. 1.21.

Equally preferred is a ratio of the length of the rectangle to the outerdiameter of the external housing ranging between 1.24 and 1.48,preferably between 1.30 and 1.42 and further preferably amounting toapprox. 1.38.

Concerning the width of the generator flange, a ratio of the width ofthe rectangle to the outer diameter of the external housing is preferredwhich ranges between 1.01 and 1.23, preferably between 1.06 and 1.17 andfurther preferably amounts to approx. 1.12.

In accordance with a tenth major aspect of the invention, the inflatorcomprises an igniter unit having a marker. The marker facilitatesmounting of the igniter unit in which the latter has a predeterminedorientation. This is advantageous especially against the background thatthe electric connecting pins of the igniter have to be mountedorientated in the inflator in order to later ensure a correct pluggingof the counter plug in the interface/cavity of the igniter carrier ofthe igniter unit. The tool which during assembly of the inflatorsupplies the pre-mounted igniter unit in an orientated fashion to theinflator component into which the igniter unit is inserted need not“enter” the sensitive interface of the igniter carrier to this end. Thusthe sensitive connecting pins of the igniter are not exposed tounnecessary tool contact.

Especially a milled slot offers itself as marker.

Simplified handling results from the fact that the igniter unit is apre-assembled unit having an igniter carrier and an igniter containedtherein which is preferably adapted to be inserted in a bottom orificeof a closing member of the inflator.

In accordance with an eleventh major aspect of the invention, theinflator comprises a diffuser which forms a preferably substantiallyrotation-symmetric external housing of the inflator with a closingmember, wherein the wail thickness of the closing member is larger atleast in portions than that of the diffuser. This aspect is based on thefinding that a greater wall thickness of the closing member is ofadvantage for receiving one or more igniter units, whereas acomparatively smaller wall thickness of the diffuser permits a desiredbulging of the diffuser in the case of activation.

Accordingly, it is provided in a preferred design that the closingmember has a substantially plane bottom in which at least one orifice isformed for receiving the igniter carrier. At least the bottom has agreater wail thickness than the diffuser.

In accordance with a twelfth major aspect of the invention, the inflatorcomprises a combustion chamber component at least partially enclosing acombustion chamber, especially a combustion chamber sleeve, and adiffuser having a ceiling portion. The axial distance between thecombustion chamber component and the ceiling portion varies related to acentral axis of the diffuser. With a symmetric curvature of the ceilingportion and a perpendicular arrangement with respect to the central axisof the portion of the combustion chamber component opposed to theceiling portion, this corresponds to an arrangement of the combustionchamber component offset with respect to the central axis.

Of preference, the combustion chamber component contacts the ceilingportion of the diffuser in a non-activated state of the inflator atleast at one position. Due to the distance between the combustionchamber component and the ceiling portion provided at the otherpositions, the combustion chamber component (combustion chamber sleeve)can be tilted as it is provided according to the special functioning ofthe second activating stage of the inflator.

The tilting is promoted by a configuration showing the largest axialdistance between the combustion chamber component and the ceilingportion of the diffuser at the central axis of the diffuser whichpreferably continuously decreases with an increasing radial distancefrom the central axis.

According to a preferred embodiment, the maximum distance between thecombustion chamber component and the ceiling portion of the diffuserranges between 2.3 and 3.7 mm, preferably between 2.7 and 3.3 mm, andfurther preferably amounts to approx. 3.0 mm.

Likewise an igniter sleeve offset with respect to the central axis ofthe diffuser can be provided whose axial distance from the ceilingportion of the diffuser varies in a similar way, especially by the factthat the axial distance of the igniter sleeve from the ceiling portionof the diffuser preferably continuously decreases with an increasingradial distance from the central axis of the diffuser.

According to a preferred embodiment, the maximum distance between theigniter sleeve and the ceiling portion of the diffuser is between 2.1and 3.5 mm, preferably between 2.5 and 3.1 mm, and further preferablyamounts to approx. 2.8 mm.

In accordance with a thirteenth major aspect of the invention, theinflator comprises a first combustion chamber associated with a firstactivating stage of the inflator and a second combustion chamberassociated with a second activating stage of the inflator. The secondcombustion chamber is surrounded at least partially by the firstcombustion chamber and has a smaller volume than the first combustionchamber. This arrangement and dimensioning of the combustion chamberspermits a structure of a two-stage inflator that is extremely compactalso in the radial direction.

An efficient configuration provides that the ratio of the volume of thefirst combustion chamber to the volume of the second combustion chamberis between 2.07 and 3.78, preferably between 2.41 and 3.21, and furtherpreferably amounts to approx. 2.82.

Another efficient configuration provides that the ratio of the volume ofthe first combustion chamber to the volume of an igniter sleeve at leastpartially surrounded by the first combustion chamber is between 9.0 and35.0, preferably between 11.6 and 22.0, and further preferably amountsto approx. 15.5.

The above-mentioned ratios are advantageous especially in an inflatordesign in which the ratio of the outer diameter of an external housingof the inflator to the height of the external housing is between 1.38and 1.78 and further preferably amounts to approx. 1.57.

Such inflator whose construction height, especially the axial height ofan external housing of the inflator, ranges between 30 and 50 mm andpreferably amounts to approx. 40 mm, is particularly suited for a driverairbag module in a vehicle comprising an airbag having a volume of 40 to60 liters.

Another efficient configuration provides that the ratio of the volume ofthe first combustion chamber to the volume of the second combustionchamber is between 2.34 and 3.27, preferably between 2.54 and 3.00, andfurther preferably amounts to approx. 2.76.

Another efficient configuration provides that the ratio of the volume ofthe first combustion chamber to the volume of an igniter sleeve at leastpartially surrounded by the first combustion chamber is between 13.5 and31.0, preferably between 16.0 and 24.0, and further preferably amountsto approx. 19.3.

The last stated ratios are advantageous especially with an inflatordesign in which the ratio of the outer diameter of an external housingof the inflator to the height of the external housing is between 0.94and 1.16 and further preferably amounts to approx. 1.05.

Such inflator whose construction height especially the axial height ofan external housing of the inflator, ranges between 50 and 70 mm andpreferably amounts to approx. 60 mm, is particularly suited for apassenger airbag module in a vehicle comprising an airbag which has avolume of 60 to 135 liters.

In general, very large airbags can be inflated by the extremely compact“disk-shape” inflator according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention are resulting from thefollowing description and from the attached drawings that are referredto, in which:

FIG. 1 is a sectional side view of an inflator according to theinvention of a first configuration.

FIG. 2 is a sectional side view of an inflator according to theinvention of a second configuration.

FIG. 3 is a sectional top view of a diffuser of an inflator according tothe invention.

FIG. 4 is a sectional side view of the diffuser of FIG. 3.

FIG. 5 is a sectional top view of a diffuser of an inflator according tothe invention.

FIG. 6 is a lateral sectional view of an igniter carrier of an inflatoraccording to the invention.

FIG. 7 illustrates the igniter carrier of FIG. 6 including an insertedpacking ring.

FIG. 8 illustrates the igniter carrier of FIG. 7 including an insertedigniter.

FIG. 9 illustrates the igniter carrier and the igniter of FIG. 9 in thepre-assembled state.

FIG. 10 is a lateral sectional view of a closing member of an inflatoraccording to the invention.

FIG. 11 illustrates the closing member of FIG. 10 including insertedigniter units.

FIG. 12 is a partial top view of the closing member and the igniterunits of FIG. 11.

FIG. 13 is a perspective view of an igniter sleeve of an inflatoraccording to the invention according to a first embodiment.

FIG. 14 is a lateral sectional view of the igniter sleeve of FIG. 13.

FIG. 15 is a sectional view along the line of cut A-A of FIG. 14.

FIG. 16 is a lateral sectional view of an igniter sleeve according to asecond embodiment.

FIG. 17 is a lateral sectional view of an igniter sleeve according to athird embodiment.

FIG. 18 is a sectional view along the line of cut A-A of FIG. 17.

FIG. 19 is a perspective view of an igniter sleeve according to a fourthembodiment.

FIG. 20 is a lateral sectional view of the igniter sleeve of FIG. 19.

FIG. 21 is a sectional view along the line of cut A-A of FIG. 20.

FIG. 22 is a sectional view along the line of cut C-C of FIG. 20.

FIG. 23 is a perspective view of an igniter sleeve according to a fifthembodiment.

FIG. 24 is a lateral sectional view of the igniter sleeve of FIG. 23.

FIG. 25 is a sectional view along the line of cut A-A of FIG. 24.

FIG. 28 is a sectional view along the line of cut C-C of FIG. 25.

FIG. 27 is a top view of an inflator according to the invention partlycut in a lower area of the inflator.

FIG. 28 is a partly cut perspective view of an inflator according to theinvention without diffuser.

FIG. 29 is a lateral sectional view of an inflator according to theinvention according to the second configuration after activation of thesecond activating stage.

FIG. 30 is a lateral sectional view of an inflator according to theinvention without diffuser and fill member.

FIG. 31 shows a cut-out from a lateral sectional view of an inflatoraccording to the invention.

FIG. 32 is a top view of a fill member part for the first combustionchamber of an inflator according to the invention in accordance with anembodiment.

FIG. 33 is a perspective view of the fill member part of FIG. 32.

FIG. 34 is a top view of an inflator according to the invention cut inan upper area of the inflator.

FIG. 35 is a top view of a filter of an inflator according to theinvention.

FIG. 36 is a sectional view of the filter along the line A-A in FIG. 35,and

FIG. 37 is a schematic lateral sectional view of an inflator accordingto the invention in accordance with the first configuration in anembodiment.

DESCRIPTION

In the following detailed description of preferred embodiments andvariants of the invention indications such as at the top, bottom etc.are used for a better comprehension. These indications relate to anorientation of the inflator as shown in the FIGS. 1 and 2.

It is understood that individual features or groups of featuresdescribed in connection with a configuration and/or an embodiment mayalso be the subject matter or element of any other configuration and/orembodiment, even if this is not expressly mentioned once againhereinafter. Each of the described sleeve variants or individualfeatures of the same can be provided in any of the configurations, forinstance. Also, the filter/diffuser designs, designs of dischargeorifices and the other features can be combined at will.

In FIG. 1 an inflator which is part of an airbag module having aninflatable airbag is shown according to a first configuration. Theinflator comprises an external housing which is composed of a cup-shapeddiffuser 10 and a closing member 12.

The diffuser 10 includes a curved ceiling portion 14 and a substantiallycylindrical circumferential wall 16 connected thereto. A generatorflange 18 extends radially outwardly from the side of thecircumferential wall 16 facing away from the ceiling portion 14.Hereinafter the generator flange 18 shall not be considered to be partof the external housing.

The closing member 12 has a substantially plane bottom 20 and an outercircumferential pulled up edge 22 which is adjacent to the inside of thecircumferential wall 16 of the diffuser 10. The wall thickness of theclosing member 12 is larger at least in portions than that of thediffuser 10. Especially the bottom 20 of the closing member 12 isthicker than the circumferential wall 16 and the ceiling portion 14 ofthe diffuser 10.

The external housing formed of the diffuser 10 (without generator flange18) and the closing member 12 is substantially rotation-symmetric withrespect to the central axis A of the inflator, as it is usual for socalled “disk-shape” inflators which also include the subject matter ofthe invention. The central axis A of the inflator thus coincides withthe central axis of the diffuser 10 and the closing member 12.

The closing member 12 includes two bottom orifices 24 differently spacedapart from the central axis A of the inflator which serve for receivingpre-assembled igniter units 28, 28. Both igniter units 26, 28 comprise arespective igniter carrier 30 and 32 and a respective igniter 34 and 36inserted in the former.

The first igniter unit 20 (left in FIG. 1) is associated with a firstactivating stage of the inflator. An igniter sleeve 38 open at one sidewhose bottom 40 is opposed to the ceiling portion 14 of the diffuser 10is attached to a receiving portion of the first igniter carrier 30.Between the igniter sleeve 38 end the first igniter carrier 30 a pressfit is provided so that no further fastening measure (welding etc.) isnecessary. The igniter sleeve 33 encloses an igniter chamber 42 intowhich the first igniter 34 projects. The igniter chamber 42 is filledwith a booster charge (not shown), especially in the form of tablets.

The igniter sleeve 38 is completely surrounded by a first combustionchamber 44 which is filled with a fuel (not shown), especially in theform of tablets. As can be recognized from FIG. 1, the diameter of theigniter sleeve 38 is tapered step by step towards its bottom 40. Thetapering leaves more space for fuel in the first combustion chamber 44compared to an igniter sleeve having a constant diameter.

The first combustion chamber 44 is axially confined by the callingportion 14 of the diffuser 10 and the bottom 20 of the closing member12. Radially the first combustion chamber 44 is confined by a completelycircumferential annular filter 46 which extends along the inner side ofthe pulled up edge 22 of the closing member 12 or along the inner sideof the circumferential wall 16 of the diffuser 10, with an annular gap48 being formed between the filter 46 and the circumferential wall 16.

Below the filter 46 the first combustion chamber 44 is confined inradial direction by a supporting element 50 on which the filter 46 isaxially supported, in the case of a not completely circumferentialsupporting element 50, the first combustion chamber 44 is confined inthe areas lying there between by the edge 22 of the closing member 12.The fact that the filter 46 does not extend to the bottom 20 of theclosing member 12 allows saving costs for additional filter material andweight.

Between the fuel of the first combustion chamber 44 and the ceilingportion 14 of the diffuser 10 a first fill member 52 is arranged.According to the first embodiment illustrated in FIG. 1, the first fillmember 52 is made of expanded metal (knitted mesh) and includes elasticfinger-type portions 54 supported toward the ceiling portion 14 of thediffuser 10.

The second igniter 36 (on the right in FIG. 1) protrudes into a secondcombustion chamber 56 which is surrounded at least partially by thefirst combustion chamber 44. The second combustion chamber 56 issubstantially confined by a fuel canister 58 made of aluminum, copper,plastic material or steel and a combustion chamber sleeve 60 made ofsteel surrounding the fuel canister 58.

The fuel canister 58 has a substantially cylindrical side wall 62. On anaxial end face facing the ceiling portion 14 of the diffuser 10 the fuelcanister 58 includes a fuel canister opening 64; in the shown embodimentsaid end face is completely open. At the opposite end face the fuelcanister 53 includes a fuel canister bottom 66 having a central fuelcanister bottom opening 68. The fuel canister bottom opening 68 isformed by a bent inner edge portion 70 extending from the fuel canisterbottom 66 into the interior of the fuel canister 68. The fuel canisterbottom 66 having the bent inner edge portion 70 is supported on an upperreceiving portion of the second igniter carrier 32. A press fit isprovided between the fuel canister 58 and the second igniter carrier 32so that no further fastening measure (welding etc.) is required.

The fuel chamber sleeve 60 is pushed onto the fuel canister 58 inopposite orientation so that a fuel chamber sleeve bottom 72 opposed tothe ceiling portion 14 of the diffuser 10 completely closes the openside of the fuel canister 58. The free edge 74 at the open side of thecombustion chamber sleeve 60 is attached to a lower receiving portion ofthe second igniter carrier 32. A press fit is provided between thecombustion chamber sleeve 60 and the second igniter carrier 32 so thatno further fastening measure (welding etc.) is required.

At the combustion chamber sleeve bottom 72 a second fill member 76tightly connected to the same is arranged that protrudes into the fuelcanister 58. Otherwise the second combustion chamber 56 is filled withfuel (not shown), especially in the form of tablets.

Hereinafter the basic functioning of the inflator is described. Specialfeatures of the functioning shall further below be explained in detail.

As mentioned already, the inflator is designed in two stages. Uponactivation of the first stage the first igniter 34 ignites the boostercharge in the igniter chamber 42. During combustion of the boostercharge “igniting jets” (hot gas) escape from overflow orifices of theigniter sleeve 38 (not visible in FIG. 1), which will be discussed indetail later, into the first combustion chamber 44 and ignite the fuelprovided there. The gas formed during combustion flows through thefilter 46 cooling the gas and freeing it from particles and subsequentlythrough discharge orifices 78 of the diffuser 10 which will equally bediscussed in detail later into the airbag.

Upon activation of the second stage which, in response to the recognizedsituation of accident and the activation control, can basically takeplace after, before or independently of the first stage, the secondigniter 36 ignites the fuel in the second combustion chamber 56. The gasformed during combustion of the fuel can escape from the secondcombustion chamber 56 into the first combustion chamber 44 by a specialmechanism which will be described in detail later. From there the gasflows through the filter 46 and the discharge orifices 78 into theairbag.

The structure of the inflator shown in FIG. 1 (first “high”configuration) permits inflating an airbag having a volume of 60 to 135liters and thus is suited especially for passenger airbag modules.

The construction height of the inflator, especially the axial height h1of the external housing, in the first configuration ranges between 50and 76 mm and in the shown embodiment according to FIG. 1 is approx. 60mm.

In the first configuration of the inflator the ratio of the volume ofthe first combustion chamber 44 to the volume of the second combustionchamber 56 ranges between 2.34 and 3.27, preferably between 2.54 and3.00. In the shown embodiment according to FIG. 1 this ratio is approx.2.76.

In the first configuration of the inflator the ratio of the volume ofthe first combustion chamber 44 to the volume of the igniter sleeve 38ranges between 13.5 and 31.0, preferably between 16.0 and 24.0. In theshown embodiment according to FIG. 1 this ratio is approx. 19.3.

In the first configuration of the inflator the ratio of the outerdiameter a of the external housing of the inflator (without generatorflange 18, cf. FIG. 5) to the height h1 of the external housing isbetween 0.94 and 1.16 and in the shown embodiment according to FIG. 1amounts to approx. 1.05.

FIG. 2 illustrates a second configuration of the inflator having adefinitely lower constructional height compared to the firstconfiguration and accordingly is also referred to as “flat”configuration. The structure of the inflator in both configurations issubstantially identical with several exceptions. Hereinafter the mostimportant differences will be discussed.

Compared to the first configuration, in the second configuration theaxial extensions of the closing member 12, the igniter sleeve 38, thefuel canister 58, the combustion chamber sleeve 66, the igniter chamber42 and the two combustion chambers 44, 56 reduced.

In the second configuration the filter 46 extends from the ceilingportion 14 of the diffuser 10 to the bottom area of the closing member12. At its lower end the filter 46 is axially supported on an inclinedtransition area 80 of the closing member 12, therefore in this case aseparate supporting element for the filter 46 as in the firstconfiguration is not provided.

Instead of the first fill member 52 of expanded metal including theelastic finger-type portions 54, according to a second embodiment a flatfirst fill member 82 of resilient silicone is provided. The embodimentof the first fill member 82 shown in FIG. 2 can also be employed in thefirst configuration. The second embodiment of the first fill member 82will be discussed in detail further below.

The structure of the inflator shown in FIG. 2 (second “flat”configuration) permits inflating an airbag having a volume of 40 to 60liters and is thus especially suited for driver airbag modules.

The construction height of the inflator, especially the axial height h2of the external housing, in the second configuration ranges between 30and 50 mm and in the shown embodiment according to FIG. 2 is approx. 40mm.

In the second configuration of the inflator the ratio of the volume ofthe first combustion chamber 44 to the volume of the second combustionchamber 56 ranges between 2.07 and 3.78, preferably between 2.41 and3.21. In the shown embodiment according to FIG. 2 this ratio amounts toapprox. 2.82.

In the second configuration of the inflator the ratio of the volume ofthe first combustion chamber 44 to the volume of the igniter sleeve 38is between 9.0 and 35.0, preferably between 11.6 and 22.0. In the shownembodiment according to FIG. 2 this ratio is approx. 15.5.

In the second configuration of the inflator the ratio of the outerdiameter a of the external housing of the inflator to the height h2 ofthe external housing is between 1.38 and 1.78 and in the shownembodiment according to FIG. 2 is approx. 1.57.

Hereinafter different peculiarities of the inflator illustrated in FIGS.1 and 2 are described.

The FIGS. 3 and 4 show the diffuser 10 of the inflator which is formedto be substantially rotation-symmetric except for the generator flange18. In the circumferential wail 16 extending substantially in parallelto the central axis A a plurality of discharge orifices 78 are provided.The discharge orifices 78 era throughout disposed in a row extending ata constant height in circumferential direction. More precisely, allcenters of the discharge orifices 78 have the same axial distance fromthe radially extending generator flange 18.

In the row more than twelve, preferably more than fourteen dischargeorifices 78 are provided. In the shown embodiment it is an odd number:exactly twenty-three discharge orifices 78 are arranged in a row. Ingeneral, the ratio of the outer circumference of the diffuser 10 inmillimeters to the number n of the discharge orifices in the row is lessthan 16.5, preferably less than 14.1, further preferably less than 9.85.Further preferably the ratio ranges between 7.57 and 9.85, furtherpreferably between 8.20 and 8.96. In the shown embodiment this ratio isapprox. 8.56.

As indicated in FIG. 4, at the inside of the diffuser 10 the dischargeorifices 78 are covered by a tamping in the form of a circumferentialtamping strip 84. The dimensions of the tamping strip 84 are selectedsuch that it fits in the annular gap 48 between the circumferential wall16 of the diffuser 10 and the circumferential filter 46 (cf. FIGS. 1 and2).

The row of the discharge orifices 78 is not completely circumferential.Viewed clockwise, the discharge orifice denoted with 78 a marks thebeginning and the discharge orifice denoted with 78 b denotes the end ofthe row. Within the row the distances between neighboring dischargeorifices 78 (related to the centers thereof) are equal. The distancebetween the first discharge orifice 78 a and the last discharge orifice78 b, on the other hand, is twice as large. Since the number n of thedischarge orifices 78 in the row is odd, thus the arrangement of thedischarge orifices 78 is such that—related to the central axis A—eachdischarge orifice 78 is opposed to another discharge orifice, with oneexception: The discharge orifice denoted with 78 c is opposed to thearea between the first discharge orifice 78 a and the last dischargeorifice 78 b and thus to no discharge orifice. In this area of thediffuser inside a joint of the tamping strip 84 is disposed. Here adischarge orifice would impair the tightness to the outer area of theinflator.

In general, the angular distance between neighboring discharge orifices78 in such a constellation (irrespective of whether the number n of thedischarge orifices is even or odd) amounts to 360°/(n+1).

The preferably circular discharge orifices 78 have at least twodifferent flow cross-sections; in the shown embodiment there are a totalof three different flow cross-sections. The discharge orifices 78 aretherefore provided with the addition (1), (2) or (3) in FIG. 3 so as tomark the relevant flow cross-section. The different flow cross-sections(1), (2) and (3) are defined by different diameters of the dischargeorifices 78.

The flow cross-sections (1), (2) and (3) of the discharge orifices 78are selected such that opposite discharge orifices 78 have equal flowcross-sections. On the other hand, neighboring discharge orifices 78within the row have different flow cross-sections. In the shownembodiment the following sequence of the flow cross-sections is repealedin the row: small flow cross-section (1)→medium flow cross-section(2)→small flow cross-section (1)→large flow cross-section (3).

The ratio of the outer circumference of the diffuser 10 (withoutgenerator flange 18) in mm to the number of the discharge orifices 78having a small flow cross-section (1) is less then 19.7 and preferablyis between 15.1 and 19.7. in the shown embodiment this ratio is approx.17.9.

The ratio of the outer circumference of the diffuser 10 in mm to thenumber of the discharge orifices 78 having a medium flow cross-section(2) as well as to the number of the discharge orifices 78 having a largecross-section (3) is less than 39.4 and preferably is between 28.2 and39.4. in the shown embodiment this ratio amounts to approx. 32.8.

The ratio of the total flow cross-section of all discharge orifices 78in the row in mm² to the outer circumference of the diffuser 10 in mm ismore than 110 and preferably ranges between 110 and 139. In the shownembodiment this ratio is approx. 124.

It is evident from the top view of the diffuser 10 of the inflatorillustrated in FIG. 5 that the generator flange 18 radially outwardlyextending from the circumferential wall 16 of the diffuser 10 has asubstantially rectangular shape. The central axis A of therotation-symmetric external housing having circular cross-sectionextends across the center M of the generator flange 18.

The ratio of the length l to the width b of the rectangle describing thegenerator flange 18 ranges between 1.12 and 1.31, preferably between1.16 and 1.27. In the shown embodiment this ratio is approx. 1.21.

The ratio of the length l of the rectangle to the outer diameter a ofthe external housing (without generator flange 18) is between 1.24 and1.48, preferably between 1.38 and 1.42. In the shown embodiment thisratio is approx. 1.36.

The ratio of the width b of the rectangle to the outer diameter a of theexternal housing is between 1.01 and 1.23, preferably between 1.06 and1.17. In the shown embodiment this ratio is approx. 1.12.

In the FIGS. 6 to 9 different steps of assembling one of the igniterunits 26, 28 are illustrated, before the latter is inserted as apre-assembled unit into one of the bottom orifices 24 of the closingmember 12. First, in the igniter carder 30 or 32 shown in FIG. 6 apacking ring 86 is inserted in an igniter seat (cf. FIG. 7), before theigniter 34 or 36 is inserted in the igniter seat of the igniter carrier30 or 32 (cf. FIG. 8). After that, the projecting circumferential edge88 of the igniter seat is beaded such that the igniter 34 or 36 issafely held in the igniter carrier 30 or 32 (cf. FIG. 9).

At a particular position the igniter carrier 30 or 32 has a milled slotas marker 90. The marker 90 provides an orientation of the igniter unit26 or 28. A mounting tool used for assembling the inflator is designedso that it can receive the igniter unit 26 or 28 in a predeterminedorientation only. When mounting the igniter unit 26 or 23, it is mountedin the desired orientation by means of the appropriate tool (cf. FIGS.10 to 12).

FIGS. 13 to 26 show different embodiments of the igniter sleeve 33 whichis arranged on the first igniter carrier 30 at a predeterminedorientation. To this end, the igniter sleeve 38 has a marker 92 distantfrom its central axis B or extending non-symmetrical from the centralaxis B. By means of the marker 92 it is possible to ensure the correctorientation of the igniter sleeve 38 during attachment onto the firstigniter unit 26.

In the embodiment of the igniter sleeve 33 shown in FIGS. 13 to 15 themarker 92 is in the form of a nose extending radially outwardly from atapered portion 94 of the side wall 96 of the igniter sleeve 33.Similarly to the igniter unit 26 and 23 provided with the marker 90, amounting tool used for assembling the inflator includes a recesscorresponding to the nose so that the igniter sleeve 38 can beaccommodated in the mounting tool at a predetermined orientation only.The mounting tool is adjusted such that when mounted the igniter sleeve38 is attached to the first igniter carrier 30 at the orientation shownin FIG. 27.

In FIG. 16 another embodiment of the igniter sleeve 38 is shown. Thebottom 40 of the igniter sleeve 38 is inclined at a predetermined anglevis-à-vis a plane perpendicular to the central axis B of the ignitersleeve 38. The slant of the igniter sleeve bottom 40 is adapted to theaxial curvature of the ceiling portion 14 of the diffuser 10 so that theigniter sleeve 38 fits below the ceiling portion 14 of the diffuser 10at the predetermined orientation only.

Further alternative embodiments of the igniter sleeve 38 having specialmarkers 92 are illustrated in the FIGS. 17 and 18, 19 to 22 and 23 to26.

When activating the first state of the inflator, the igniter sleeve 38is moved upwards, i.e. in the direction of the ceiling portion 14 of thediffuser 10, by the pressure developed during combustion of the boostercharge. The maximum movement of the igniter sleeve 38 is confined by theceiling portion 14 of the diffuser 10 which in turn is deformed(bulging). In contrast to the combustion chamber sleeve 60 (as will beexplained further below) the igniter sleeve 38 does not detach from thereceiving portion of the first igniter carrier 30, i.e. by raising theigniter sleeve 38 no additional discharge orifice leading out of theigniter chamber 42 is formed.

All embodiments of the igniter sleeve 38 have in common that—related tothe central axis B of the igniter sleeve 38—they have overflow orifices98 unevenly spaced in circumferential direction. More precisely, theoverflow orifices 98 are restricted to a particular area of the sidewall 96 of the igniter sleeve 38. When the igniter sleeve 33 is attachedto the first igniter carrier 30 at the predetermined orientation, theoverflow orifices 98 are not directed directly to the filter 46. Thecentral axes of the outer overflow orifices 98 in the particular area ofthe side wail 96 define in circumferential direction a limited angularrange α for the discharge of the hot gas (igniting jets) when burningthe booster charge in the igniter chamber 42 (cf. FIG. 15).

As indicated in FIG. 27, the angular range α extends to both sides of aconnecting line between the central axis B of the igniter sleeve 38 andthe portion of the filter 46 maximally distant from the central axis B.Especially the angular range α includes those areas of the firstcombustion chamber 44 filled with fuel which have a maximum distancefrom the filter 46 not blocked by components of the inflator. Theangular range α is obtuse and is between 90° and 135°, preferablybetween 100° and 120°. In the shown embodiment according to FIG. 27 theangular range α is approx. 110°.

As is equally visible from FIG. 27, the angular range α also includesthe combustion chamber sleeve 66. The overflow orifices 98 are disposedsuch that the emitting igniting jets are not directed directly to thecombustion chamber sleeve 60, however, but mostly to areas in which asmuch fuel as possible is covered over an as large length as possible.

From FIG. 28 the particular structure of the second combustion chamber56 is evident. The bottom 66 of the fuel canister 58 is supported on asubstantially horizontal surface of the second igniter carrier 32, andthe bent edge portion 70 of the fuel canister bottom 66 is supported ona circumferential outer surface of the second igniter carrier 32. Thefuel canister 58 thus stands stably and can conveniently be filled withfuel.

After filling the combustion chamber sleeve 60 is slipped with thesecond fill member 76 onto the fuel canister 58 at an oppositeorientation (compared to the fuel canister 58). According to the shownembodiment, the fuel chamber sleeve 60 having a slightly larger axialheight than the fuel canister 58 is slipped on until the free edge 74 ofthe open side of the combustion chamber sleeve 60 is held by the lowerreceiving portion of the second igniter carrier 32 and the fuel canisteropening 64 (here: the open side) is completely covered by the combustionchamber sleeve bottom 72. Then the substantially cylindrical side walls62, 102 of the fuel canister 58 and of the combustion chamber sleeve 60are immediately opposed to each other, more precisely the loner shell ofthe side wall 102 of the combustion chamber sleeve covers the outershell of the side wall 62 of the fuel canister substantially over theentire axial length of the two sleeves 58, 60.

In the vicinity of the fuel canister opening 64, approximately at theheight of the second fill member 76 protruding into the fuel canister58, in the side wail 62 of the fuel canister 58 a preferably completelycircumferential bead 104 is embossed. The bead 104 serves forreinforcing the fuel canister 58, especially in the upper area close tothe fuel canister opening 64.

In the fuel canister bottom 66 plural fuel canister bottom holes 106 areformed. The side wall 62 of the fuel canister 58, on the other hand,includes no openings or holes. The combustion chamber sleeve 60 slippedonto the fuel canister 58 is completely tree of holes, apart from itsopen side.

Prior to activating the second stage of the inflator, the secondcombustion chamber 56 is completely closed. In the case of activation ofthe second stage, the fuel burns off in the second combustion chamber 56and the burning gas formed generates excessive pressure in the secondcombustion chamber 56. The combustion chamber sleeve 60 is forced towardthe ceiling portion 14 of the diffuser 10 by the excessive pressure.

A marginal area 108 of the combustion chamber sleeve bottom 72 distantfrom the central axis A of the inflator contacts the ceiling portion 14of the diffuser 10 either already in the non-activated state of theinflator or after a slight upward displacement of the combustion chambersleeve 60. In each case the ceiling portion 14 which itself bulges dueto the formation of gas restricts the axial movement of the combustionchamber sleeve 60.

Since the combustion chamber sleeve 60 is supported at the marginal areaof the ceiling portion 14, due to the continuously provided pressure inthe second combustion chamber 56 the combustion chamber sleeve 60 tiltsabout the contact point 110, as shown in FIG. 29. It is also possiblethat the combustion chamber sleeve 60 deforms unevenly in addition oralternatively to the tilting. In any case, a portion of the side wall102 of the combustion chamber sleeve 60 facing away from the outer edgeof the inflator is raised from the second igniter carrier 32 andreleases a discharge gap 112 which is visible especially in the detailedmagnification X of FIG. 29.

The gas formed during combustion of the fuel in the second combustionchamber 56 flows through the holes 106 in the fuel canister bottom 66 tothe discharge gap 112 and through the same from the second combustionchamber 56 into the first combustion chamber 44. According to anotherembodiment of the fuel canister 58, initially the latter exhibits nofuel canister bottom holes 106; the holes are formed as late as by thepressure developed during combustion of the fuel and tearing of the fuelcanister bottom 66 caused thereby.

The distance between the central axis B of the igniter sleeve 38 and thecentral axis C of the combustion chamber sleeve 60 represented in FIG.30 in the mounted state ranges between 22.5 and 27.5 mm, preferablybetween 23.5 and 26.5 mm. In the shown embodiment this distance isapprox. 25 mm.

The ratio of the minimum inner diameter c of the combustion chambersleeve 60 to the minimum inner diameter d of the igniter sleeve 38 isbetween 1.64 and 2.83, preferably between 1.83 and 2.32, in the shownembodiment this ratio is approx. 2.06.

The first combustion chamber 44 of the inflator is radially confined, asmentioned already, at least partially by the circumferential filter 46.The ratio of the inner diameter f of the filter 46 to the minimum innerdiameter d of the igniter sleeve 38 is between 3.19 and 4.76, preferablybetween 3.50 and 4.27. In the shown embodiment this ratio is approx.3.85.

The ratio of the inner diameter f of the filter 46 to the minimum innerdiameter c of the combustion chamber sleeve 60 is between 1.66 and 2.11,preferably between 1.76 and 1.99. In the illustrated embodiment thisratio is approx. 1.87.

The ratio of the outer diameter a of the inflator, more precisely theexternal housing (without taking the generator flange 18 into account),to the minimum inner diameter d of the igniter sleeve 38 is between 4.09and 5.98, preferably between 4.46 and 5.39. In the shown embodiment thisratio preferably is approx. 4.89.

The ratio of the outer diameter a of the inflator to the minimum innerdiameter c of the combustion chamber sleeve 60 is between 2.13 and 2.66,preferably between 2.24 and 2.5. In the shown embodiment this ratioamounts to approx. 2.38.

As can also be inferred from FIG. 30, the axial height of the contactarea between the igniter sleeve 38 and the first igniter carrier 30 islarger than the axial height of the contact area between the combustionchamber sleeve and the second igniter carrier 32.

In FIG. 31 the arrangement of the igniter sleeve 38 and the combustionchamber sleeve 60 relative to the ceiling portion 14 of the diffuser 10is shown. Related to the central axis A of the diffuser 10, both theaxial distance g between the combustion chamber sleeve 60 and theceiling portion 14 and the axial distance i between the igniter sleeve38 and the ceiling portion 14 are varying. In the shown embodiment thecombustion chamber sleeve 60 contacts the ceiling portion 14 of thediffuser 10 already in the non-activated state of the inflator at thecontact point 110 in the outer marginal area of the inflator.

The axial distance g between the combustion chamber sleeve 60 and theceiling portion 14 of the diffuser 10 is largest at the central axis Aof the diffuser 10 and continuously decreases with an increasing radialdistance from the central axis A. The maximum distance g is between 2.3and 3.7 mm, preferably between 2.7 and 3.3 mm. In the illustratedembodiment this maximum distance g is approx. 3.0 mm.

The axial distance i of the igniter sleeve 38 disposed next to thecentral axis A of the diffuser 10 is not constant either, butcontinuously decreases with an increasing radial distance from thecentral axis A of the diffuser 10. The maximum distance i between theigniter sleeve 38 and the ceiling portion 14 of the diffuser 10 isbetween 2.1 and 3.5 mm, preferably between 2.5 and 3.1 mm. In theillustrated embodiment this maximum distance i is approx. 2.8 mm.

In the FIGS. 32 and 33 one respective pad 114 of the first two-part fillmember 82 of the second embodiment is shown which is arranged in thefirst combustion chamber 44 between the fuel and the ceiling portion 14of the diffuser 10 and can be used both with the high firstconfiguration (cf. FIG. 1) and with the flat second configuration (cf.FIG. 2). The first fill member 82 made of silicone can also be in onepiece. In the two-part design of the first fill member 82 the two parts114 preferably exhibit the double half-moon shape shown in FIGS. 32 and33.

In the inserted state, the first fill member 82 has two recesses 116,118 into which the igniter sleeve 38 and the combustion chamber sleeve60 protrude. The smaller first recess 116 is circular and is adapted tothe upper outer diameter of the igniter sleeve 38. The larger secondrecess 118 is equally circular and is adapted to the upper outerdiameter of the combustion chamber sleeve 60.

The ratio of the diameter of the larger second recess 118 to thediameter of the smaller first recess 116 is between 1.52 and 2.25,preferably between 1.67 and 2.03. In the shown embodiment this ratio isapprox. 1.84.

FIG. 34 is a section across the inflator according to the firstconfiguration (cf. FIG. 1) showing the filter 46 in an upper area of theinflator. The filter 46 which is separately illustrated in FIGS. 35 and36 includes a critical filter portion 120 which comes closer to thecombustion chamber sleeve 60 than the other areas of the filter 46.

Said critical filter portion 120 has a reduced thickness compared to theadjacent areas of the filter 46. In this way a gap 122 is formed betweenthe combustion chamber sleeve 60 and the critical filter portion 120.The critical filter portion 120 is compressed in radial direction, i.e.the filter material is more compressed in the critical filter portion120 than in the adjacent areas.

The combustion chamber sleeve 60, on the other hand, exhibits anincreased material thickness in the area opposed to the critical filterportion 120 (cf, also FIGS. 1 and 5). In the shown embodiment the upperpart of the combustion chamber sleeve 60 is thickened over its completecircumference.

The ratio of the minimum radial thickness j of the critical filterportion 120 to the thickness k of the adjacent areas of the filter 46 isbetween 0.43 and 0.93, preferably between 0.53 and 0.78. In the shownembodiment this ratio is approx. 0.65.

The ratio of the minimum radial thickness j of the critical filterportion 120 to the maximum width m of the gap 122 between the combustionchamber sleeve 60 and the critical filter portion 120 is between 1.17and 2.85, preferably between 1.50 and 2.23. In the shown embodiment thisratio is approx. 1.83.

As is evident from the FIGS. 1 and 2 as well as from FIG. 37, the filter46 generally extends in axial direction beyond the circumferential wall16 of the diffuser 10 extending in axial direction into the area of theclosing member.

In the embodiment of the high first configuration of the inflatorillustrated in FIG. 37 no separate support element 50 is provided forthe filter 46. Rather, the pulled up edge 22 of the closing member 12includes at least one supporting portion 124 constituting an axialsupport for the filter 46. The supporting portion 124 can be formed by acompletely circumferential embossed bead or by plural beads spaced apartin circumferential direction. The filter 46 is supported on thesupporting portion or portions 124 only by a radially outer area.

LIST OF REFERENCE NUMERALS

-   10 diffuser-   12 closing member-   14 ceiling portion-   16 circumferential wall-   18 generator flange-   20 bottom-   22 edge-   24 bottom orifices-   26 first igniter unit-   28 second igniter unit-   30 first igniter carrier-   32 second igniter carrier-   34 first igniter-   36 second igniter-   33 igniter sleeve-   40 igniter sleeve bottom-   42 igniter chamber-   44 first combustion chamber-   46 filter-   48 annular gap-   50 supporting element-   52 first fill member (first embodiment)-   54 finger-type portions-   56 second combustion chamber-   58 fuel canister-   60 combustion chamber sleeve-   62 fuel canister side wall-   64 fuel canister opening-   66 fuel canister bottom-   63 fuel canister bottom opening-   70 marginal portion-   72 combustion chamber sleeve bottom-   74 free combustion chamber sleeve edge-   76 second fill member-   78 discharge orifices-   78 a first discharge orifice (beginning of row)-   78 b last discharge orifice (end of row)-   78 c discharge orifice without opposite discharge orifice-   78(1) discharge orifice having small flow cross-section-   78(2) discharge orifice having medium flow cross-section-   78(3) discharge orifice having large flow cross-section-   80 transition area-   82 first fill member (second embodiment)-   84 tamping strip-   86 packing ring-   88 igniter carrier edge-   90 marker of the igniter carrier-   92 marker of the igniter sleeve-   94 tapered portion-   96 igniter sleeve side wall-   98 overflow orifices-   102 side wall of combustion chamber sleeve-   104 bead-   106 fuel canister bottom holes-   108 marginal area of fuel chamber sleeve bottom-   110 contact point-   112 discharge gap-   114 fill member pad-   116 first recess of first fill member-   118 second recess of first fill member-   120 critical filter portion-   122 gap-   124 supporting portion-   A central axis of inflator, diffuser and closing member-   a outer diameter of inflator (without generator flange)-   h1 axial height of external housing (first configuration)-   h2 axial height of external housing (second configuration)-   n number of discharge orifices in the row-   M center of generator flange-   l length of rectangular flange-   b width of rectangular flange-   B central axis of rectangular flange-   α angular range-   x connecting line-   C central axis of combustion chamber sleeve and fuel canister-   c minimum inner diameter of combustion chamber sleeve-   d minimum inner diameter of igniter sleeve-   f inner diameter of filter-   g axial distance between combustion chamber sleeve and ceiling    portion-   i axial distance between igniter sleeve and ceiling portion-   j minimum thickness of critical filter portion-   k thickness of the remaining filter-   m maximum width of gap

The invention claimed is:
 1. An inflator for a protective device in avehicle, comprising a diffuser cooperating with a closing member to forman external housing of the inflator, wherein the diffuser includes aplurality of discharge orifices; a combustion chamber component at leastpartially enclosing a combustion chamber; and a ring-shaped filterextending about an axis and the combustion chamber, the filter includinga critical filter portion positioned closest to the combustion chambercomponent that has a reduced radial thickness compared to a remainder ofthe filter such that the filter is asymmetric about the axis.
 2. Theinflator according to claim 1, wherein the radial cross-section of thecritical filter portion is different from the radial cross-section ofthe remainder of the filter.
 3. An inflator for a protective device in avehicle, comprising a diffuser forming a substantiallyrotation-symmetric external housing of the inflator with a closingmember, wherein the diffuser includes a plurality of discharge orificesarranged in a row, and which are of circular shape; and a filter and acombustion chamber component at least partially enclosing a combustionchamber, wherein the filter extends in a ring-shaped manner about anaxis and the combustion chamber and includes a critical filter portionwhich is closer to the combustion chamber component than a remainingarea of the filter, wherein the critical filter portion has a reducedthickness compared to areas of the filter that are adjacent to thecritical filter portion such that the filter is asymmetric about theaxis.
 4. The inflator according to claim 3, wherein between thecombustion chamber component and the critical filter portion a gap isformed; wherein a material of which the filter is made is compressedmore highly in the critical filter portion than in the adjacent areas;wherein the combustion chamber component has an increased materialthickness at least in an area opposed to the critical filter portion;wherein the filter extends along a circumferential wall of the inflatorsurrounding a chamber of the inflator in which the combustion chambercomponent is disposed; and wherein the combustion chamber componentextends over a larger axial height than the filter, the combustionchamber component substantially exhibiting an increased materialthickness only in an axial area in which also the filter extends.
 5. Theinflator according to claim 3, wherein a gap is formed between thecombustion chamber component and the critical filter portion; wherein aratio of the minimum thickness (j) of the critical filter portion to athickness of the adjacent areas of the filter is between 0.43 and 0.93;wherein a ratio of a minimum thickness of the critical filter portion toa maximum width of the gap is between 1.17 and 2.85; and wherein theinflator is closed at a first axial end face by a substantially axiallyextending circumferential wall of the diffuser, wherein the filterextends in an axial direction beyond the circumferential wall.
 6. Theinflator according to claim 3, further comprising a radially projectinggenerator flange, related to a central axis (A) of the inflator, formounting the inflator to a support, wherein the generator flange issubstantially rectangular; wherein a ratio of a length (l) to the width(b) of the rectangle ranges between 1.12 and 1.31; wherein a ratio ofthe length (l) of the rectangle to an outer diameter (a) of the externalhousing ranges between 1.24 and 1.48; and wherein a ratio of the width(b) of the rectangle to the outer diameter (a) of the external housingis between 1.01 and 1.23.
 7. The inflator according to claim 3, whereinat least in portions a wall thickness of the closing member is largerthan that of the diffuser, wherein the closing member has asubstantially planar bottom in which at least one opening for receivingan igniter carrier is formed and that at least the bottom has a largerwall thickness than the diffuser.
 8. The inflator according to claim 3,wherein the diffuser includes a ceiling portion and the combustionchamber component contacts the ceiling portion of the diffuser in anon-activated state of the inflator at least at one point, and wherein,related to a central axis (A) of the diffuser, an axial distance betweenthe combustion chamber component and the ceiling portion is varying suchthat a maximum distance between the combustion chamber component and theceiling portion of the diffuser is between 2.3 and 3.7 mm.
 9. Theinflator according to claim 3, wherein an igniter sleeve offset withrespect to a central axis (A) of the diffuser whose axial distance (i)from a ceiling portion of the diffuser is varying such that the maximumdistance (i) between the igniter sleeve and the ceiling portion of thediffuser is between 2.1 and 3.5 mm.
 10. An airbag module for a vehiclecomprising an airbag having a volume of 40 to 60 liters, comprising aninflator according to claim
 3. 11. An airbag module for a vehiclecomprising an airbag having a volume of 60 to 135 liters, comprisinginflator according to claim
 3. 12. The inflator according to claim 3,wherein the radial cross-section of the critical filter portion isdifferent from the radial cross-section of the remainder of the filter.13. The inflator according to claim 3, further comprising an igniterunit, wherein the igniter unit has a marker, wherein the marker is amilled slot, and wherein the marker sets a predetermined orientation ofconnecting pins of the igniter unit.
 14. The inflator according to claim13, wherein the igniter unit is a pre-assembled unit having an ignitercarrier and an igniter held therein which is adapted to be inserted in abottom orifice of the closing member of the inflator.
 15. The inflatoraccording to claim 3, further comprising a fuel canister filled withfuel including a fuel canister bottom and a fuel canister openingopposed to the fuel canister bottom which is closed by the combustionchamber component.
 16. The inflator according to claim 15, wherein thecombustion chamber component is a combustion chamber sleeve whichencloses at least partially the combustion chamber associated with aparticular activating stage of the inflator, wherein the combustionchamber sleeve exhibits a combustion chamber sleeve opening or an openside and a combustion chamber sleeve bottom opposed thereto which coversthe fuel canister opening, wherein a second fill member connected to thecombustion chamber sleeve bottom is arranged at the combustion chambersleeve bottom; and wherein at least part of a side wall of the fuelcanister extending between the fuel canister opening and the fuelcanister bottom is directly opposed to at least part of a side wall ofthe combustion chamber sleeve extending between the combustion chambersleeve orifice or the open side of the combustion chamber sleeve and thecombustion chamber sleeve bottom.
 17. The inflator according to claim15, wherein the fuel canister and the combustion chamber component aretwo open substantially cylindrical sleeves which are inserted into eachother at opposed orientation so that an inner or outer shell of the fuelcanister and an outer or inner shell of the combustion chamber componentsubstantially cover each other over an entire axial length of theshells, the combustion chamber component being slipped onto an outsideof the fuel canister.
 18. The inflator according claim 15, wherein inthe fuel canister bottom a central fuel canister bottom opening isformed for receiving an igniter carrier, wherein the fuel canisterbottom opening is formed by a bent inner edge portion extending from thefuel canister bottom into an interior of the fuel canister.
 19. Theinflator according to claim 15, wherein plural holes are formed in thefuel canister bottom, and wherein the combustion chamber component isfree of holes, apart from a combustion chamber component orifice or theopen side, and wherein the combustion chamber component is slipped ontoan igniter carrier.
 20. An inflator for a protective device in avehicle, comprising: a diffuser forming a substantiallyrotation-symmetric external housing of the inflator with a closingmember, wherein the diffuser includes a plurality of discharge orificesarranged in a row, and which are of circular shape; a filter and acombustion chamber component at least partially enclosing a firstcombustion chamber, wherein the filter extends in a ring-shaped mannerabout the first combustion chamber and includes a critical filterportion which is closer to the combustion chamber component than aremaining area of the filter, wherein the critical filter portion has areduced thickness compared to areas of the filter that are adjacent tothe critical filter portion; wherein the first combustion chamber isfilled with fuel which is associated with a first activating stage ofthe inflator and is closed on one side by the diffuser, wherein a firstfill member is disposed between the fuel and the diffuser, wherein thefirst fill member has at least one circular recess into which an ignitersleeve associated with the first activating stage of the inflator or acombustion chamber sleeve associated with a second activating stage ofthe inflator projects; wherein the first fill member has two recesses ofdifferent size, wherein the igniter sleeve projects into a smallerrecess and the combustion chamber sleeve projects into a larger recess;wherein a ratio of the diameter of the larger recess to the diameter ofthe smaller recess is between 1.52 and 2.25; and wherein the first fillmember is designed in at least two parts that each has a shape of adouble half moon.